ION-SELECTIVE SOLVENT POLYMERIC MEMBRANE ELECTRODES BASED ON 1-PHENYL-3-METHYL-4-ACYL-5-PYRAZOLONES FOR TRIVALENT LANTHANOID IONS

Abstract

Potentiometric responses of liquid membranes incorporating 1-phenyl-3-methyl-4-acyl-5-pyrazolones having different 4-acyl groups were investigated to trivalent lanthanoid, aluminum, transition metal, alkaline and alkaline earth metal ions at pH 5.5. Nernstian responses to Yb3+ in the concentration range from 10−6−10−5 M to 10−2 M were observed with membranes based on the ligands with long 4-n-alkanoyl or 4-benzoyl groups, and the responses were smaller with membranes containing the shorter 4-n-alkanoyl and bulky 4-acyl derivatives as sensory elements. For all the membranes examined, potentiometric responses to Mn2+, Co2+, Ni2+, Zn2+, alkaline (Na+, K+) and alkaline earth metal (Mg2+, Ca2+, Sr2+, Ba2+) ions were negligible, whereas interferences of the other trivalent ions and Cu2+ were large. The potentiometric selectivity to Yb3+ over Gd3+ and La3+ was better for membranes based on 4-acyl-5-pyrazolones with a longer n-alkyl chain, and deteriorated for membranes based on the ligands with a bulky 4-acyl gr...